Bacterial diversity and flavor profile of Zha-Chili, a traditional fermented food in China

Zha-chili is a traditional Chinese fermented food with special flavor, which is often used as an appetizer in condiments and an important energy source. The final quality of zha-chili is closely related to its microbial community structure. However, the differences of bacterial diversity in zha-chili from different regions and how bacterial species affect zha-chili fermentation process and flavor quality have not been reported. In this study, the bacterial diversity and flavor quality of zha-chili samples from different regions were analyzed using Illumina Miseq high-throughput sequencing, electronic nose and electronic tongue technology. Twenty-three bacterial phyla and 665 bacterial genera were identified in all zha-chili samples. Firmicutes, Proteobacteria and Actinobacteria were the dominant bacterial phyla in zha-chili samples, while Lactobacillus, Pseudomonas, Pediococcus, Weissella and Staphylococcus were the dominant bacterial genera. The bacterial community structure of zha-chili samples from different regions was significantly diverse (p < 0.05). The flavor of zha-chili samples also varied in different regions, and the discrepancy of taste was much greater than that of aroma. Moreover, there were significant correlations (p < 0.05) between 6 dominant bacterial genera and 8 flavor indicators (3 aroma indicators, 5 taste indicators). In addition, the results of microbiome phenotypes prediction by BugBase and bacterial functional potential prediction using PICRUSt showed that eight out of nine predicted phenotypic functions of zha-chili samples from different regions were significantly different (p < 0.05), bacterial metabolism was vigorous in the zha-chili samples, and Lactobacillus was the dominant bacterial genus involved in metabolism during fermentation.